..Both trichochromes are efficient quenchers of 1O2, exhibiting a bimolecular rate constant comparable with vitamin C. These results suggest that trichochromes could serve a protective role in pheomelanin pigments...

..This provides new insights into the potential contribution of iridal stroma melanosomes both to inducing oxidative stress and to accounting for the observed iris-color-dependent epidemiology of uveal melanoma...

Insight into the binding of divalent cations to Sepia eumelanin from IR absorption spectroscopy

..Several previously reported values can be reconciled with the current measurement by careful consideration of thermodynamics associated with the presence of competing ligands used to solubilize copper...

..9 x 10(5) M(-1), was smaller than the largest constant for HSA by a factor of approximately 7. The binding constant for OTA with D3, 1.1 x 10(5) M(-1), was very close to that of the secondary binding site for HSA...

Quantification of Ca(2+) binding to melanin supports the hypothesis that melanosomes serve a functional role in regulating calcium homeostasis

..While the structural and functional roles of melanosomal lipids largely remain to be determined, these different lipid compositions reported herein offer new insights into the roles of melanosomes in the different ocular tissues...

..These tissue-related and age-related chemical differences between samples affected the optic density and metal binding properties of melanosomes, which are believed to be closely associated with the biological functions of melanins...

Aggregation of eumelanin mitigates photogeneration of reactive oxygen species

..g., small oligomeric species, such as dimers and trimers) relative to WT and A53T. Thus, we propose that the high affinity site is attributed to the binding of Cu(II) to those small oligomeric species...

..2). On the basis of the reported optical properties of synthetic models, this result suggests that the absorption of pheomelanin is less than eumelanin at wavelengths of biological relevance ( approximately 315-400 nm)...

..The combination of ultrafast absorption and photoacoustic data suggest photoexcitation produces a long-lived intermediate and the energy of this species is at least 133 kJ mol(-1) above the ground state of the dTC molecule...

..This difference should enable us to map out their respective distribution in tissue samples with subcellular resolution. This technique could provide valuable information in diagnosing the malignant transformation of melanocytes...

..The 580 and 1470 cm(-1) bands are assigned to Fe-OR stretching and ring deformation modes, respectively. These data further substantiate that the Fe(III)-melanin-binding site in melanin is composed of CAT-like structural units...

..Such a kinetic model would predict a structural motif with pheomelanin at the core and eumelanin at the surface, which is consistent with the measured surface oxidation potential of the approximately 30-nm constituents of NM granules...

Identification and quantification of dolichol and dolichoic acid in neuromelanin from substantia nigra of the human brain

..The distribution of dol-CA chains lengths in NM also differed from that of dol, suggesting that the enzyme(s) responsible for the conversion of dol to dol-CA prefer a dolichol substrate containing 19 isoprene units...

Mechanistic studies on the photochemical deprotection of 3',5'-dimethoxybenzoin esters

..As the composition, absorption, and fluorescence of lipofuscin undergo age-related changes, the purpose of this study was to determine whether photoreactivity of lipofuscin granules also changes with the donor age...

Different molecular constituents in pheomelanin are responsible for emission, transient absorption and oxygen photoconsumption

..This raises concern about comparing the results from different photochemical methodologies for melanin, which is a specific case of comparing data on systems where molecular constituents are not well defined...

Effects of photodegradation on the physical and antioxidant properties of melanosomes isolated from retinal pigment epithelium